How to cross pollinate beans (genus Phaseolus)
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- เผยแพร่เมื่อ 16 ก.ย. 2024
- Here is the method we use for pollinating beans of the genus Phaseolus at the University of California, Davis. The method of making crosses in beans is simple (no emasculation required) and highly efficient, with at least a 90% success rate and essentially a 0% selfing rate.
This works on common bean (Phaseolus vulgaris, e.g. green bean, pinto bean, black bean, kidney bean, etc), Lima bean (Phaseolus lunatus), tepary bean (Phaseolus acutifolius), and runner bean (Phaseolus coccineus).
Thanks a lot. That's exactly what I was looking for!
Glad it was useful!
Very helpful video, thank you. I’ve tried a couple of times to cross beans but was stymied because thought I could not find any pollen. I have done pea crosses and they’re relatively easy - no messy pistil curling and gobs of bright yellow pollen! I thought beans would be the same. Wrong! Keen to try again next bean season.
I’m guessing that the same or similar methods apply to Vigna species. I’m interested in crossing some cowpeas, though I’d have to do something about ants which are mad for the nectaries near the flower base!
Thank you so much for very helpfull video👍👍
Thank you for your video. When is a new variety stabilized if you want it to become stabilized?
Wow I have been looking for a video like this for a while. I watched your spanish version first and my spanish is apparently still good enough to get most of what you said. But watching in English helped a bit. ;) Hooking the two stigmas together is a good trick. Also excellent point on the seed coat being maternal tissue.
Thanks! Yeah making cross-pollinations in beans is really crazy, you can get so many different progeny from any cross! One other thing I should have mentioned is that it is best to do this when it is cool, ideally in the morning and on cooler days
@@travisparkerplantscience right because high night time temperatures can block fertilization in beans. I have run into that problem with just bean pod production here in Missouri in midsummer from my pole beans. Flowers will form but the ovary just drops with the flower. I tried Tepary beans as a possible substitue for P. vulgaris but in our relatively moist climate they hardly produced anything. I have heard about hybrids between Tepary and Common bean but I read they require embryo rescue in the first generation. I hadn't heard of any varieties being released from those crosses yet. I had pretty good luck with Vigna species though. :)
@@Biophile23 That's right! The good news about crossing is that (usually) you only need one F1 plant though, so if it is hot and your crossing success rate isn't as high, it should still be okay as long as you get one. You're right about tepary / common bean hybrids needing embryo rescue, there are some newer releases where some ancestry comes from one species or the other, but it is hard to transfer complex traits like heat tolerance :/
Hi @@travisparkerplantscience thanks for the awesome vid. What do you mean with you need only one F1? Wouldn't the multiple F1's look different? So I'm guessing you would need more than one to see if you get the result you hoped for. Or do you mean that you don't need to breed till F8 to get a stable hybrid /true from seed?
@@Optimistforreal Beans self-pollinate (except for the relatively rare cross-pollination by a bee or human), the result of this is that homozygosity builds up and they become very stable and homozygous. So assuming your parents are quite homozygous (which tends to be a safe assumption, unless you made a cross), all the progeny look the same.
An example with one gene: If one parent is AA and one is aa, the only possible offspring are Aa, and they are all the same for that gene. With four genes, if one parent is AABBCCDD and the other parent is aabbccdd, the only possible progeny are AaBbCcDd. They will therefore all be the same for these genes. Humans and many other species have siblings that are quite different because each parent is (hopefully) quite heterozygous, but this is not the case in many inbreeding self-pollinating crops. I hope that makes sense!
Helpful
You mentioned that you wouldn’t know if it was a successful cross until the following season. If a pinto and black bean cross, what would the beans come out looking like? I’m going to try crossing a pole flat bean with a bush flat bean I like. Is getting a pole/bush mix possible or will it likely be one or the other. Thanks! Great video
Great question! A cross between a black and pinto bean will almost always give you a black bean in the next generation (often with somewhat bigger seeds like the pinto parent). If you let those set seeds, you will get all kinds of combinations, including pintos and black beans, and often all kinds of other types beyond what is seen in either parent. Crossing pole with bush beans almost always give you a pole bean in the F1, but if you let those self-pollinate you will get both bush and pole-types back in the second generation.
Long story short: Make crosses and in two or three generations you will have all kinds of cool combinations of the traits you started with and much more! I usually make sure the mother has some recessive characteristics (bush type, lighter seed/flower color) so you can know quickly if your crosses were successful.
@@travisparkerplantscience thank you! So one has a purple flower (marvel of Venice) an the other white (early Italian), so it would be best if the white one was the mother? If I saw plants in F2 or F3 that had characteristics I liked how many further generations would it take for those characteristics to stabilize and become true to type? Would just seed saving from these plants allow for that?
@@farmerjon7598 More great questions. Yes, I would use the white-flowered type as the mother, and the offspring should have purple flowers (or at least some kind of color). You will see about 25% of F2s have white flowers. With every generation starting at the F2, the instability is cut in half, so any given F2 has 1/2 of genes still variable, an F3 is 1/4 variable, F4s 1/8 variable, etc. All you have to do is let them self pollinate in the field. We usually select our favorite F5 or so, but there is no right or wrong way to do it. We released a variety that is descended from a single (surprisingly stable) F3, and others we have taken to the F10!
Wouldn't you have to emasculate the flower you cross pollinate?
Sorry just read the description, although I dont understand why
@@jorrit3118 That's a great question! In Phaseolus we don't have to emasculate. In a normal Phaseolus flower without human intervention, the anthers (pollen-producing structures) break open and shed pollen as the stigma pushes through, in the early morning as the flowers open, and the stigma gets coated in pollen. In this method, we open the mother flower prematurely, before the anthers break open, and the stigma pushes through before the anthers are ready. So that mother plant's stigma is not coated in pollen. Once the stigma pushes through it won't go back in or come in contact with the anthers, so we don't have to worry about self-pollination!
@@travisparkerplantscience Thanks for the clarification!
What is the success rate of doing Phaseolus crosses in the field vs. in the greenhouse?
are there any barriers to cross pollination of mungblean flower? what is it?
Actually I do not want that my runnerbeans cross polinate. Any ideas how to do it? Maybe how far appart should I plant them? And how to tell the insects that they are not allowed to cross polinate?
Hi, haha good questions! Runner beans are tricky... they are the only domesticated Phaseolus bean that will not self-pollinate, unless someone does it manually! The flowers of most other beans will self-pollinate in the absence of insects or people. So it will be tricky, sometimes we self-pollinate the runner beans by hand (this must be done in the greenhouse, where there are no insects). But to get seed, something needs to pollinate, and if you have many varieties in an area, the bees will move the pollen around! So I would say there isn't a clear distance that bees couldn't / wouldn't cross. You can self-pollinate if needed, otherwise, the further the better, if you don't want outcrossing!
Both male and female looks same here in video. Can’t distinguish